Field
This disclosure relates to an electrostatic capacitive type touch screen panel.
Related Art
In recent years, display devices, such as a liquid crystal display, an electroluminescent display, and a plasma display panel, having a quick response speed, low power consumption, and an excellent color reproduction rate, have been in the spotlight. These display devices have been used for various electronic products such as a television, a monitor for a computer, a laptop computer, a mobile phone, a display unit of a refrigerator, a personal digital assistant, and an automated teller machine. In general, these display devices interface with various input devices such as a keyboard, a mouse, and a digitizer. However, in many types of input devices, a user has to learn how to use the input devices, making it difficult for the user to properly operate the products. Furthermore, the input device occupies a separate space, which increases the overall size of the appliances or devices incorporating these input devices. Thus, there has been an increasing demand for simple and convenient input devices. A touch screen panel is an input device that mitigates or removes such drawbacks in other types of input devices. The touch screen panel allows users to provide user input by directly touching the screen with the users' finger or a pen.
The touch screen panel is currently being applied to various display devices, because it has simple structure and robust operation, and the user can perform an input action without using a separate input device, and can quickly and easily manipulate the devices through contents displayed on a screen.
Touch screen panels are classified into a resistive type, a capacitive type, an electromagnetic type and so on according to a detection method of a touched position. The resistive type touch screen panel detects a touched position by a voltage gradient according to resistance in a state that a DC voltage is applied to metal electrodes formed on an upper plate or a low plate. The capacitive type touch screen panel senses a touched position according to a difference in capacitance created in an upper or lower plate when the user touches an equipotential conductive film formed on the upper or lower plate. The electromagnetic type touch screen panel detects a touched position by reading an LC value induced as an electromagnetic pen touches a conductive film.
Hereinafter, a related art electrostatic capacitive type touch screen panel will be described with reference to FIGS. 1 to 2B. FIG. 1 is a top plan view of a related art electrostatic capacitive type touch screen panel, FIG. 2A is a top plan view of a region R shown in FIG. 1 and FIG. 2B is a cross-sectional view taken along line I-I′ of region R shown in FIG. 2A in which the related art electrostatic capacitive type touch screen panel is coupled with a display device.
Referring to FIGS. 1 to 2B, the related art electrostatic capacitive type touch screen panel includes a touch electrode forming part TA, a routing wire forming part RA, and a pad forming part PA.
The touch electrode forming part TA includes a plurality of first touch electrode serials TS1 to TS5 (touch driving electrode serials or touch sensing electrode serials) and second touch electrode serials RS1 to RS6 (touch sensing electrode serials or touch driving electrode serials) formed on a transparent substrate 10. The plurality of first touch electrode serials TS2 to TS5 are arranged in parallel in a first direction (e.g., the x-axis direction). The plurality of second electrode serials RS1 to TS6 are arranged in a second direction (e.g., the y-axis direction) to cross over the first electrodes TS.
Each of the first electrode serials TS1 to TS5 has a plurality of first electrode patterns Tx which are connected to each other. Each of the second electrode serials RS1 to RS6 has a plurality of second electrode patterns Rx and bridge patterns BP. Each of the bridge patterns BP connects two second electrode patterns Rx which are neighbored to each other. The neighbored two electrode patterns Rx are connected to each other by the bridge pattern BP exposed via contact holes formed in an insulation layer INS.
The routing wire forming part RA includes a plurality of first routing wires TW1 to TW5 and a plurality of second routing wires RW1 to RW6 which are formed outside the touch electrode forming part TA. The plurality of first routing wires TW1 to TW5 are connected with the first touch electrode serials TS1 to TS5, respectively, and the plurality of second routing wires RW1 to TW6 are connected with the second touch electrode serials RS1 to RS6, respectively.
The pad forming part PA includes a plurality of first pads TP1 to TP5 and a plurality of second pads RP1 to RP6. The plurality of first pads TP1 to TP5 are connected to the plurality of first touch electrode serials TS1 to TS5 via the plurality of first routing wires TW1 to TW5, respectively. The plurality of second pads RP1 to RP6 are connected to the plurality of second touch electrode serials RS1 to RS6 via the plurality of second routing wires RW1 to RW6, respectively.
In the related art electrostatic capacitive type touch screen panel, there is a variation of mutual capacitance between the first electrode pattern Tx and the second electrode at before and after a touch when user touches the touch electrode forming area TA by using conductor or fingers. Accordingly, it is possible to detect touch positions by using the variation of mutual capacitance between before and after of the touch.
In order to easily perceive a touch, it is advantaged the more the variation of mutual capacitance is large. In general, the related art touch screen panel has various mutual capacitances, such as a first mutual capacitance C1 generated by linear type near electric field between the first touch electrode serials TS1 to TS5 and the second touch electrode serials RS1 to RS6, a second capacitance C2 generated by curved type far electric field between them, and a parasitic capacitance C3 generated by electric field between the first and second touch electrode serials TS1 to TS5 and RS1 to TS6 and display electrodes (not shown) as shown in FIG. 2A.
The first mutual capacitance C1 is little affected by a touch, thus little to generate a variation of mutual capacitance between before and after the touch. The second mutual capacitance C2 is greatly affected by a touch. The parasitic capacitance C3 increases time constant which affects a charge characteristic between the first and second touch electrode serials TS1 to TS5 and RS1 to RS6, thereby reducing the charge characteristic. On the other hand, at areas excluding the touched area, the first and second mutual capacitance C1 and C2 are functioned as a parasitic capacitance, thereby lowering a touch sensibility.
In particular, in the related art touch screen panel, the parasitic capacitance C3 between the first touch electrode serials TS1 to TS5 and the second touch electrode serials RS1 to RS6 are large because the first and second electrode serials TS1 to TS5 and RS1 to RS6 have a similar size.
Also, in the related art touch screen panel, edges of the first touch electrode Tx and edges of the second touch electrode Rx opposite to each other are linearly formed in parallel as shown FIGS. 2A and 2B. An entire mutual capacitance formed between the first and second touch electrodes Tx and Rx is not sufficient because a path of mutual capacitance between the first and second touch electrodes Tx and Rx is formed in the shortest distance.
In the related art touch screen panel, there are some problems lowering touch sensibility because the parasitic capacitance is increased and the variation rate of the second mutual capacitance among the entire mutual capacitance is low.